US20160366991A1 - Mold-in touch fastening product - Google Patents

Abstract

A male touch fastener strip includes an elongated base and a field of male fastener elements each having a stem extending from a broad face of the base and a head for engaging fibers. The fastener element stems and broad face of the base together form a unitary mass of resin, such as a resin containing a magnetically attractable substance. Wings extend from respective longitudinal edges of the base and define discrete corrugations extending in a series along the fastener strip and forming corresponding undulations in the rear face of the strip along its longitudinal edges. The corrugated wings can also support a foam gasket.

Description

TECHNICAL FIELD
• The present invention relates to touch fastening products, and more particularly to touch fastening products configured to be incorporated into molded articles.
BACKGROUND
• Traditionally, hook-and-loop fasteners comprise two mating components that releasably engage with one another, thus allowing coupling and decoupling of the two surfaces or objects. The male fastener portion typically includes a substrate having fastener elements, such as hooks, extending from the substrate. Such fastener elements are referred to as “loop-engageable” in that they are configured to releasably engage with fibers of the mating component to form the hook- and loop-fastening.
• Among other things, hook-and-loop fasteners are employed to attach upholstery to car seat cushions. Car seat cushions are typically made of a foam material. To attach the upholstery to the foam, one fastener product is incorporated at a surface of the foam car seat and the mating component is incorporated into the upholstery, or is provided by the upholstery itself. The male fastener elements releasably engage with the mating component to couple the upholstery to the foam car seat.
• To incorporate a male fastener product into a foam cushion, the fastener product may be positioned within a cushion mold, such that as foam fills the mold to form the cushion, the foam adheres to the fastener product. Flooding of the fastener elements by the foam during forming of the cushion is generally seen as inhibiting the usefulness of the fastener elements, and so several improvements have been made to attempt to avoid such foam intrusion.
• Further advances in the design of fastener products are sought, for this and for other applications.
SUMMARY
• One aspect of the invention features a male touch fastener strip having a front fastening face and a rear face, The strip has an elongated base, a field of exposed male fastener elements each having a stem extending from the base on the front fastening face of the strip, and a pair of wings, each wing extending from a respective longitudinal edge of the base outboard of the field of fastener elements. Each wing defines discrete corrugations extending in a series along the fastener strip and forming corresponding undulations in the rear face of the strip along longitudinal edge regions of the fastener strip.
• In some cases, a side of the base opposite the fastener elements is essentially planar, and at least a portion of each undulation may extend at least partially rearward of the side of the base opposite the fastener elements.
• The series of the corrugations may have a frequency of between 4 and 20 corrugation cycles per inch (2 and 8 per cm) along the fastener strip, for example.
• In some examples the wings are each angled, in an unloaded state, toward the rear face of the strip. In some cases the elongated base defines a lateral plane containing its elongated edges, and in some fastener strips the wings each form a midpoint angle (defined with respect to the midpoint of the corrugation pattern) of between about 5 and 80 degrees (or between about 25 and 70 degrees) with respect to the lateral plane.
• In some cases the corrugations define a corrugation amplitude, at outer edges of the wings, of at least two times a nominal edge thickness of the wings.
• In some configurations, the wings are of substantially constant thickness throughout the corrugations.
• The corrugations may define any of a number of different profiles at the outboard edges of the wings, such as a saw tooth profile or a sinusoidal profile, for example. The wings are also preferably void of fastener elements.
• In some embodiments, the base is of a material comprising a magnetically attractable substance dispersed throughout a synthetic resin. For example, the magnetically attractable substance may include between about 30 and 40 percent of the material, by weight. The magnetically attractable substance may be in the form of discrete particles of the substance, such as particles comprise iron-containing powder, dispersed throughout the synthetic resin, for example.
• In some examples, the wings are formed of the material, the wings and base together forming a contiguous mass of the synthetic resin. The fastener elements may also be formed of the material.
• In some fastener strips, the longitudinal edges of the fastener strip feature changes in thickness between the base and the wings. The wings may be of a nominal thickness between about 20 and 90 percent of a nominal thickness of the base, the nominal thickness of the base may be between about 0.006 and 0.013 inch, and the nominal thickness of the wings may be between about 0.002 and 0.011 inch, for example.
• In some cases the fastener strip also has longitudinal walls rising from the base on either side of the field of male fastener elements and inboard of the wings. The walls may be longitudinally continuous, and may each have a height at least as great as that of the male fastener elements.
• In some embodiments each wing carries a respective strip of foam adhered to the wing on a same side of the fastener strip as the fastener elements, and in some cases overlaying the corrugations. In some examples the fastener strip has longitudinal end regions in which the front fastening face of the strip is covered by foam forming, in cooperation with the foam strips, an end barrier of the fastener strip. The covering foam and foam strips may be portions of a seamless foam layer. In some cases the end regions of the fastener strip are void of fastener elements.
• The strips of foam may extend laterally beyond the wings, and may be adhered to the wings by adhesive.
• In some examples the fastener elements each also have a head at an upper end of the stem and overhanging the base for engaging fibers.
• Another aspect of the invention features a male touch fastener strip having a front fastening face and a rear face. The strip has an elongated base of a material comprising a magnetically attractable substance dispersed throughout a synthetic resin, and a field of exposed male fastener elements each having a stem extending from the base on the front fastening face of the strip. The base has an areal heat capacity of between about 15 and 65 (preferably, between about 45 and 65) milli-Joules per square centimeter degree C.
• For some applications, the magnetically attractable substance comprises between about 30 and 40 percent of the material, by weight.
• In some cases, the magnetically attractable substance is in the form of discrete particles of the substance (such as particles containing iron) dispersed throughout the synthetic resin.
• In some fastener strips, the base forms the rear face of the fastener strip. The base may have a nominal thickness of between about 0.003 and 0.012 inch, for example.
• In some cases the fastener strip also has longitudinal walls, such as longitudinally continuous walls, rising from the base on either side of the field of male fastener elements. The walls may also be formed of the materials.
• In some embodiments, the fastener strip also has a pair of wings, each wing extending from a respective longitudinal edge of the base and angled, in an unloaded state, toward the rear face of the strip. In some cases, each wing defines discrete corrugations extending in a series along the fastener strip and forming corresponding undulations in the rear face of the strip along longitudinal edges of the fastener strip.
• Another aspect of the invention features a method of forming a touch fastener strip. The method includes forming an elongated planar base with a field of male fastener elements extending from one broad side of the base, corrugating longitudinal edges of the elongated base to form edge corrugations, and plastically bending the longitudinal edge regions out of the plane of the base, toward a side of the touch fastener strip opposite the fastener elements.
• In some examples the method also includes, after forming the planar base and before corrugating the longitudinal edges, heating the formed base.
• In some embodiments, plastically bending the longitudinal edge regions occurs after corrugating the longitudinal edges.
• Some examples also include forming longitudinally continuous walls extending from the base on either side of the field of male fastener elements.
• Some examples of the method include adhering foam to longitudinal edge regions of the elongated base. The method may include, before adhering the foam to the longitudinal edge regions, eliminating the fastener elements in discrete regions spaced apart along the base. Adhering the foam may include adhering the foam to the base in the discrete regions, and the fastener elements may be eliminated by energy supplied by sonic horn, for example.
• The method may include, after eliminating the fastener elements in the discrete regions, applying an adhesive to the discrete regions. Adhering the foam to the longitudinal regions may also include adhering the foam to the discrete regions.
• Adhering the foam may include applying a widthwise-continuous layer of foam across the broad side of the base and over the field of fastener elements, such that the layer of foam is adhered in the longitudinal edge regions, and then removing a central portion of the foam layer to expose the field of fastener elements between remaining strips of foam adhered to the longitudinal edge regions.
• Many of the features of the examples described herein can help to promote secure attachment of the fastener strip within a foam body, such as a seat cushion. At least some of these features derive in part from the realization that providing undulations or corrugations along the edges of a fastener strip can produce a beneficial effect in the ultimate strength of the attachment of the fastener strip to the foam body. Such effects can be further enhanced by forming the edges as corrugated wings that extend toward the back (non-fastening) face of the fastener strip, and even further by supporting an open cell foam on a front side of the angled wings.
• The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
• FIG. 1 is a perspective view of an end portion of a first fastening product.
• FIG. 2 is a side view of the product ofFIG. 1.
• FIG. 3 is an enlarged top view of the product ofFIG. 1.
• FIG. 4 is a cross-sectional view taken along line4-4 inFIG. 1.
• FIGS. 5 and 6 are perspective and side views, respectively, of the product ofFIG. 1, held against the surface of a mold pedestal.
• FIG. 7 is a top view of an end region of the product ofFIG. 1, with the foam removed.
• FIGS. 8 and 9 are perspective and end views, respectively, of a second fastener product.
• FIGS. 10-12 are perspective, side and top views, respectively, of a third fastener product.
• FIGS. 13 and 14 are perspective and side views, respectively, of the product ofFIG. 10, held against the surface of a mold pedestal.
• FIG. 15 is a perspective view of a fourth fastener product.
• FIG. 16 is an end view of the fastener product ofFIG. 15, showing the product positioned in a molding trench.
• FIGS. 17 and 18 are upper and lower perspective views of a fifth fastener product.
• FIGS. 19 and 20 are upper and lower perspective views of a sixth fastener product.
• FIGS. 21-23 are front, enlarged side, and end views, respectively, of a fifth fastener product.
• FIGS. 24A-24C schematically and sequentially illustrate a process for forming a molded foam article with a fastening product embedded in one surface of the article.
• FIG. 25 schematically represents an apparatus and method for forming the fastening product ofFIG. 1.
• Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
• Referring toFIGS. 1-4, afastening product100 includes abase102,barrier walls104, ruffled orcorrugated wings106,fastener elements110, andfoam strips111 that functions as gaskets during foam molding.Base102 defines a longitudinal (i.e., lengthwise) direction101, and a lateral (i.e., widthwise) direction103 that is perpendicular to the longitudinal direction. The base is a flexible, elongated strip of resin, molded unitarily and integrally withwings106.Barrier walls104 are continuous and extend integrally from anupper surface112 of thebase102. In this example, the fastener product includes a pair of barrier walls spanning the length of the base in the longitudinal direction. Each ofbarrier walls104 are positioned inboard of a respective longitudinal edge114 ofbase102.
• When fasteningproduct100 is held against a flat surface, such as a surface of a mold pedestal (as discussed in detail below),barrier walls104 contact the mold pedestal surface to help inhibit (if not prevent) flowing resin from contactingfastening elements110. Accordingly, in this example, the height ofbarrier walls104 is at least as great as that offastener elements110. In some implementations, however,barrier walls104 can be slightly shorter than fastener elements110 (e.g., 0.004 inch or less in height). In these implementations, the barrier walls may not contact the mold pedestal surface. In some examples, a gap exists between the barrier walls and the flat surface of the pedestal that is small enough to inhibit or prevent foam intrusion. In some examples, the fastener elements are configured to bend or compress when held by force against the mold pedestal, to bring the barrier walls in contact with the flat surface of the pedestal. In some examples, a second, segmented wall (not shown) extends from the base outboard of each barrier wall and inboard of each wing, defining flow gaps into which foam flows to further help anchor the fastener product in a foam seat bun. Some examples of fastener strips also feature lateral walls (not shown) that extend across the array of fastener elements, connectingbarrier walls104 at discrete point along the length and dividing the fastener array into discrete, bounded cells. In a particular example,barrier walls104 extend fromupper surface112 ofsubstrate102 to a height of 0.051 inch, and have a thickness of 0.012 inch. In a particular example, the distance between facing surfaces ofbarrier walls104 is 0.364 inch.
• Eachcorrugated wing106 is disposed outboard of a respective barrier wall104 (in lateral direction103), extending from a longitudinal edge114 ofbase102. As shown, eachcorrugated wing106 is angled to extend toward the non-fastening side of the product, and defines a series ofedge corrugations118 along its length. In some examples, each wing has a width W1 that is between about 10 and 20 percent of the width W2 of thebase102. In this example, each wing has a width of about 2.5 mm while the base has a width of about 11 mm.Corrugations118 define undulations that have an amplitude of 1.0 mm at their outer edges (or at least twice the nominal thickness of the wing at the outer edge), and a regular wavelength of about 2.5 mm, or an undulation frequency of about 10 undulations per inch. The amplitude of the undulations decreases with distance from the outer edges, such that at the inner edges of the wings the undulations have disappeared, while the thickness of the wing resin remains generally constant throughout the length and width of the wing, such that the undulations are equally evident on the front and rear faces of the wings. The undulations may be in the form, for example, of a sinusoidal wave or a saw-tooth triangular wave (with sharp or radiused apexes). As shown inFIG. 4, the wings each extend, in an unloaded state at a midpoint angle θ of about 45 degrees, measured between the plane of the rear surface ofbase102 and a plane bisecting the undulation of the wing.
• A strip of compressible,open cell foam111 is adhered to the upper or front surface of eachwing106 with a bead of hot-melt adhesive113. (The foam and adhesive are omitted from the left wing inFIG. 4, for clarity.) As will be discussed in more detail below,foam strip111 is slightly compressed against the mold surface during foaming and both helps to prevent foam intrusion from reaching the fastener elements, and helps to anchor the product in the foam. Flowing and expanding foam at least partially penetrates into the open cells of the foam strip. The compressibility of the foam also helps to accommodate imperfections in a mold pedestal surface (e.g., scratches, dents, or uneven surfaces) that could otherwise allow foam to flow past thebarrier walls104 and into contact withfastener elements110. Uncompressed, the foam extends about three millimeters from the upper surface of each wing, or to a height of more than twice the height of the fastener elements. Angling thewings106 toward the rear of the product allows for use of thicker foam strips, enhancing the area of open cell foam accessible for penetration by the foaming resin. As evident fromFIGS. 3 and 4, when viewed from the fastening side of the strip the foam extends slightly beyond the molded resin of the strip on all sides.
• Thecorrugated wings106 help with retention of the fastener product in the foam of the seat bun. Because of the corrugations, the wings have a greater surface area than flat wings of an equivalent width. The greater surface area provides more area for bonding with foam. In this example, the wings are also thinner than the base, having a constant nominal thickness of only about 0.003 inch, whilebase102 has a nominal thickness of about 0.010 inch, such that even with the undulations the wings do not represent a significant material cost. The corrugations also act to stiffen the thin wings against bending, such that the wings generally maintain their orientation during foam molding—without the need for stiffening ribs and other projections adding mass. The corrugations also present localized flow dams that direct small amounts of foam into gaps between the wings and the foam strips111, aiding in retention, and the undulations on the rear face of the product are believed to locally alter the foam flow across the back of the fastener strip so as to disrupt the formation of larger foam cells, creating a more randomized pattern of cells that helps to avoid local weak points in the formed foam and enhance bonding to the rear surface of the fastener product.
• Fastener elements110 are flexible and extend upward fromupper surface112 ofbase102. The fastener elements are arranged in an array betweenbarrier walls104. Each offastener elements110 has a head spaced aboveupper surface112, and each head has two distal tips that extend in opposite directions to form loop overhangs (i.e., palm-tree type fastening elements). Thus, the fastener elements are configured to releasably engage fibers of a mating component (not shown) to form a hook-and-loop fastening. Other appropriate types of fastening elements can also be used. For example, J-hook and/or mushroom-type fastening elements can be implemented.
• Referring also toFIGS. 5 and 6,fastener product100 can be held against amold pedestal10. One or more portions offastener product100 can be formed of a magnetically attractable substance, such that the fastening product is attracted by a magnet to hold it against a flatmold pedestal surface12. In this example, the base, walls, fastener elements and wings of the product are all formed of a synthetic resin in which magnetically attractable substance (in particular, magnetite or an iron powder) is dispersed. As molded, all of these portions of the product together form a contiguous mass of the synthetic resin. One suitable nanosuspended composite resin has about 35 percent by weight magnetite powder of a particles size of about 10 to 40 micrometers suspended in a matrix of impact-modified nylon (such as a blend of 6 and 6-6). Whenfastener product100 is held againstmold pedestal10, its foam strips are compressed againstmold pedestal surface12 such that flow of foam is prevented from flooding the field of fastener elements.
• As shown inFIGS. 1 and 3, both ends of the fastener product are sealed against the surface of the mold withend gaskets122 of open cell foam extending across the width of the product and connecting the foam strips111.FIG. 7 shows an end of the product without the foam strips or end gaskets, showing that in anend region120 thebase102 is void of fastener elements and walls. Such a flat end region can be formed by obliterating molded fastener elements and walls near the ends of the product, before application of the foam gasket and strips, which can be supplied as a unitary foam layer, as described below.
• Referring toFIGS. 8 and 9, anotherexample fastener product200 haswings106 that are connected to base102 at hinges202.Fastener product200 is similar in its configuration tofastener product100. For example,fastener product200 includes abase102,barrier walls104, andfastener elements110. However,product200 does not include foam strips along its edges, although it may include foam end gaskets (not shown).Hinges202 are incorporated into the upper surface of the strip adjacent the outer surfaces ofbarrier walls104. In this example, hinges202 are provided in the form of continuous indentations integrally molded with thebase102 andcorrugated wings106. In some examples, the indentations are at most only half as deep as the nominal thickness of the wings. Other implementations of the hinges can also be used (e.g., perforations or folds).
• Hinges202 allow the corrugated wings of the fastener strip to flex relative tobase102. The degree of flexure is determined based on the material properties and dimensions of the hinges. Allowing the wings to flex relative to the base of the fastener strip can reduce stress near the longitudinal edges of the base. These stresses can result from various operations in forming the molded foam article. For example, in molding the article, stress is imparted on the fastening product near its longitudinal edges when foam expands adjacent the edges of the strip. High stress also occurs during other common processes such as de-molding and roller crushing. When the fastener product is secured to the molded product, the hinges allow the embedded wings to move with the cured foam. As a result, crack formation and propagation near the longitudinal edges is inhibited.
• As shown, hinges202 extend longitudinally along the length of the substrate, substantially parallel to the barrier walls of the fastening product. However, in some examples, the fastening product can include lateral hinges that traverse the width of the fastener product. The lateral hinges can be incorporated into the backside surface of the base, and disposed at predetermined intervals down the length. Incorporating lateral hinges into the fastening product can increase flexibility in the longitudinal direction, such that the fastening product is more suited for winding about a take-up roll and forming a continuous spool.
• Referring next toFIGS. 10-12,fastening product300 includes abase102,barrier walls104,corrugated wings106 andfastener elements110 as in the above embodiments, but also includeswave walls306 andlateral walls308 that also extend integrally fromupper surface112 ofbase102. Afoam relief space322 is defined between eachbarrier wall104 and itscorresponding wave wall306, which further assists in anchoring theproduct300 to a molded foam cushion. Each of the lateral walls108 extends between facing surfaces ofbarrier walls104 to define a longitudinal column ofbounded fastening cells124 containing one or more of thefastener elements110. Thewave wall306 is a continuous wall configured with a wave shape that gradually rises and/or falls along the longitudinal direction of the product so as to provide one continuous element, rather than defining a plurality of discrete elements that rise and fall abruptly by virtue of substantially vertical edges. The wave shape defined by thewave wall306 may be periodic (repetitive) as shown but need not be. In any case, when abutted against a mold pedestal used for forming foam cushions (or some other molded product), the wave shape provides one or more intentional openings or “flow gaps” that allow an appropriate amount of foam resin to flow into thefoam relief space322 during the manufacturing process, so that thefastening product300 effectively becomes integrated with or otherwise anchored to the foam cushion being formed. Not wishing to be held to a particular theory, it is believed that the gradual rising and/or falling of thewave wall306 allows the openings or flow gaps to be smaller than openings or flow gaps formed by discrete elements that rise and fall abruptly (substantially vertical rise and fall edges). In addition, the wave shape also allows thewave wall306 to be both a single continuous element and flexible in the longitudinal direction, while maintaining rigidity in the lateral direction.
• The wave shape ofwall306 can be, for example, sinusoidal, triangular, saw tooth (ramp), or any other shape that includes a gradual rising edge, or a gradual falling edge, or both gradual rising and falling edges. Alternatively,wall306 could be replaced with a series of discrete wall segments having substantially vertical edges (e.g., 90 degrees, +/−5 degrees) and defining gaps therebetween. In some embodiments, such as the one shown inFIG. 11 for example, the slope of a straight line connecting the 20% and 80% points of a given waveform edge is in the range of about 3 degrees to about 65 degrees (assuming that 0 degrees is perfectly horizontal and 90 degrees is perfectly vertical, and further assuming that the 0% point is the lowest point along a given edge and the 100% point is the highest point along that edge). Further note that the wave shape ofwall306 may be symmetrical, but need not be (e.g., rising edge can be steeper than the falling edge, or vice-versa). Further note that the wave shape ofwall306 may be repetitive the entire length of theproduct300, but need not be (e.g., multiple wave shape types may be used along the length of wall306). While only one wave wall is shown along each side of the product, multiple parallel wave walls can be provided on each side, with staggered wave patterns to form a more tortuous path for foam to flow through to reach the barrier walls. Numerous suitable wave wall configurations can be used as will be apparent in light of this disclosure.
• In this example,wings106 are corrugated to have an embossed sinusoidal wave pattern at their outer edges, with an amplitude that decreases with distance from the edge. Furthermore, in this example the wings extend generally laterally from the edges of the base and are not angled rearward. Portions of each undulation cycle may extend behind a rear surface of the base, but another portion of the cycle will extend forward ofsurface112. While this pattern is regular and of a constant amplitude and period, varying corrugation patterns are also envisioned. Furthermore, in some cases the amplitude of the corrugation may be constant over a significant width of the wing, diminishing only adjacent the base edge.
• When fasteningproduct300 is held against a flat surface, such as a surface of a mold pedestal (as shown inFIGS. 13 and 14),barrier walls104 contact the mold pedestal surface to inhibit (if not prevent) flowing foam resin from infiltratingcells124 and contactingfastening elements110. Accordingly, in such a case, the height ofbarrier walls104 is the same or greater than that offastener elements110. Eachwave wall306 is disposed outboard of arespective barrier wall104. Also evident inFIG. 13 are theundulations350 formed by the corrugations of the wings in the rear face of the fastener strip along its longitudinal edge regions.
• Referring back toFIGS. 10-12, each ofwave walls106 of this example embodiment includes a sinusoidal wave shape that includessymmetrical peaks318 andtroughs320 so as resemble a sine wave signal having a 50% duty cycle. As visible inFIG. 11,peaks318 are the same height as thebarrier wall104, and thetroughs320 are adistance142 from thebarrier wall104 top. In some example cases, for instance, the period of the wave ranges from about 0.05 to 0.2 inches (e.g., 0.09 to 0.16 inches), anddistance142 ranges from about 0.02 to 0.10 inches (e.g., 0.03 to 0.06 inches). The minimum percentage of the wave wall thattroughs320 can dip from the top of the wall will depend on factors such as the fluidity of the foam and the desired fill pattern of therelief spaces322. In some specific example cases, the ratio ofdepth142 to the overall height ofwave wall306 is in the range 5% to 50%. As will be appreciated, thedepth142 can be thought of as a peak-to-peak amplitude of the wave shape inwall306, and sized to provide a desired flow gap. To this end, the ratio can be expressed as peak-to-peak amplitude divided by overall wave wall height (as measured from top most edge to the bottom ofwave wall306 at surface112). To give some further context with respect to size ofproduct300, according to some such example embodiments, the length ofproduct300 in the longitudinal direction may be in the range of, for instance, 4 to 24 inches, and the width ofproduct300 in the lateral direction may be in the range of, for instance, 0.4 to 2.0 inches. In addition, the height of a givenproduct300 so configured could be, for example, in the range of 0.06 to 0.4 inches (as measured from the underside ofbase102 to the top of barrier wall104), wherein the fastening elements have a similar height (as measured from the underside ofbase102 to top of fastener element110).
• As previously explained, the one or more openings formed by virtue of the rising and falling of the wave shape whenproduct300 is abutted with a mold surface allow a flowable material (e.g., a liquefied or partially expanded foam) to pass over (or under, as the case may be) thewave wall306 and into the correspondingfoam relief space322. The opening(s) have an overall definable area which can be generalized as the missing portion(s) of wall306 (ifwall306 where intended to be rectangular in shape rather than wave-shaped). In some embodiments,peaks318 ofwave wall306 contact the mold surface, thereby defining a plurality of openings, while inother embodiments peaks318 ofwave wall306 do not contact the mold surface, thereby defining a single continuous wave-shaped opening. In either case, the overall area defined by the one or more openings is in the range of, for example, about 4 to 45 percent of thewall306.
• To this end, each ofwave walls106 defines an overall flow gap, formed of the one or more openings. An overall flow gap can be described as the total exposed area of all flow enabled openings of thewave wall306. In this example, each of wave peaks318 has a height equaling that ofbarrier walls104. Accordingly, each opening is widest at the lowest point oftrough320 and gradually tapers in each direction until the neighboringpeaks318 are reached so as to effectively define a series of tapered flow gaps of eachwave wall306. Each of these tapered flow gaps contributes to the overall flow gap. The tapering of the flow gap(s) is believed to contribute to better resin flow management and control, because the area of tapered flow gap can actually be smaller than a non-tapered flow gap while still allowing a better distributed flow of foam into therelief space322, thereby improving integration/anchoring of theproduct300 into the foam cushion being formed. It may be helpful to measure the dimensions of the flow gap(s) in terms of area per unit strip length ofbase102, although there are other ways to quantify and characterize the flow gap(s), such as by the slope of the rising and/or falling edges. In some examples, and as previously explained, the flow gap(s) constitute between 5 percent and 40 percent of the effective area of thewave walls106. By way of contrast, note that with a non-tapered flow control arrangement (substantially vertical rise and fall edges), the flow gaps constitute between 15 percent and 50 percent of the effective area of the non-tapered walls, based on comparison studies and evaluation. In general, it is believed to be more difficult to reliably control resin flow with a larger non-tapered flow gap area, so the reduction in flow gap area by way of gradual tapering is beneficial.
• Foam passing throughwave walls306 entersfoam relief spaces322. Thefoam relief spaces322 are delimited by arespective wave wall306 and itsnearest barrier wall104. The dimension of afoam relief space322 can be measured, for example, in terms of its volume per unit strip length ofbase102. The volume per unit strip length can be defined as the product of the distance between facing surfaces of arespective wave wall306 and itsnearest barrier wall104 and the height of thebarrier wall104. As will be appreciated in light of this disclosure, the fill pattern within thefoam relief space322 resulting from a tapered flow gap tends to be more evenly distributed than the fill pattern within thefoam relief space322 resulting from a non-tapered flow gap.
• A number of benefits associated with foam relief space will be appreciated. For instance, allowing the foam to set-up aroundwall306 and withinrelief space322 increases the bond strength betweenfastening product300 and a foam molded article, such as a seat component for automobiles, trucks, trains, planes, and other such vehicle seats. Another benefit is that, in some cases, imperfections in a mold pedestal surface (e.g., scratches, dents, or uneven surfaces) can allow foam to flow past thebarrier walls104 and into contact withfastener elements110. This can be inhibited (if not prevented), however, by permitting foam to enter and set-up infoam relief spaces322. In some examples, the cured or solidified foam can form an integral seal with the mold tool surface, preventing flow past the barrier walls. More details concerning the sizing and arrangement ofwave walls306 andrelief spaces322 can be found in pending U.S. patent application Ser. No. 14/697,838, filed Apr. 28, 2015, and incorporated by reference herein in its entirety.
• In this example,lateral walls308 laterally traverse an inner area between facing surfaces ofrespective barrier walls104 to isolate arrays offastener elements110. In some implementations, however, thelateral walls308 extend beyond thebarrier walls104, traversing the inner area between facing surfaces of theouter wave walls306.Lateral walls308, in conjunction withbarrier walls104 demarcateindividual fastening cells124. The fastener cells are effectively sealed against ingress of foam, when thefastening product300 is held against a surface of a mold pedestal. In some embodiments, eachlateral wall308 defines one or more gaps extending through the wall and connectingadjacent fastening cells124. For instance, in this example shown inFIGS. 10-12, eachlateral wall308 defines onegap126. Thegaps126 can extend from the upper surface of thebase102. Thegaps126 can also extend through an upper extent of thelateral walls308. Other appropriate gap configurations, however, can also be implemented (as will be described in turn). In still other embodiments, there are fewer or nogaps126. For instance, in one example embodiment, every otherlateral wall308 has nogap126, and is therefore continuous.
• Thegaps126 each define a lateral width. An appropriate lateral width of thegaps126 can be configured to provide certain desired properties of thefastening product300. For instance,gaps126 can be sized to simultaneously provide air-releasing capability, bending flexibility, resistance to foam intrusion, and retention. In some examples, the lateral gap width is between about 0.002 and 0.015 inches, or between about 0.004 and 0.012 inches. In one specific example case, the lateral gap width is about equal to a lateral width of afastener element110, which is sufficient to allow air-flow but not necessarily sufficient to allow flow of foam (depending on foam type and its flowability at dispensing time). In some implementations, the lateral width ofgaps126 is constant over different distances fromupper surface112. In some other implementations, the lateral width of thegaps126 tapers or otherwise varies with distance from upper surface112 (e.g., the gaps are wider at their distal extent than at a height closer to upper surface112). In any such cases, providing afastening product300 withgaps126 extending throughlateral walls308 separatingfastening cells124 can permit air to flow between thecells124 during the mold-in process, and can in some cases help to avoid undesirable lifting of the fastening product from the mold surface due to air expansion, and may equalize pressure betweencells124, helping to avoid ‘burping’ or rapid release of air from under the fastening product.Such gaps126 can also increase the flexibility of the fastening product, permitting the fastening product to more readily bend about an axis running along its length, or to otherwise conform to curved mold surfaces without buckling. Additionally, during the forming process, the foam may flow intofastener cells124 adjacent ends of the product through the gaps, which may further help to anchor the ends of the fastening product in the molded foam article.
• As shown inFIGS. 10 and 12, thelateral walls308 are disposed at predetermined intervals down the length of thebase102. In this manner,lateral walls308 allowfastener product300 to be manufactured in continuous spools that can be severed to form various lengths of fastening strips, without the need of applying any foam end gaskets. In some examples, the inner surfaces of thelateral walls308 are spaced apart from one another by between about 0.3 and 1.0 inches (e.g., about 0.5 inches in one specific example embodiment). In some examples, a continuous spool of the fastener product can be severed so as to leave a number offastening elements110aexposed to foam (as shown inFIG. 10). The exposedfastening elements110acan act as additional anchor points to the molded foam article. Further, as withbarrier walls104 and wavewalls306,lateral walls308 can extend integrally fromupper surface112. The height oflateral walls308 can be equal to that ofbarrier walls104.
• Referring next toFIG. 15product400 is a clip retainer that is embedded in the bottom of a foam trench of a seat bun, for retaining associated clips (not shown) to attach a seat cover trim strip. In this example, the product has a segmented base that allows the strip to be articulated to follow a curved trench, for example. Each base segment carries a pair of laterally directed, spaced apart hooks54 extending upward from a continuous base, and a pair ofguide walls46 on either side. The guide walls extend upward at a slight angle. Further details of the general structure and use ofproduct400 in a fastening system can be found in pending PCT application number PCT/EP2014/054554, filed Mar. 10, 2014, and incorporated herein by reference.
• The lateral ends of each base segmentfeature wing segments58 that are angled toward the non-fastening side of the product. Each wing segment features one or more undulations molded into its outer edge. With the product placed into a trench in a mold, as shown inFIG. 16, thewing segments58 extend away from the mold surface and are thereby embedded in foam during a subsequent molding operation. Ametal wire60 molded into the product at the base of thehooks54 is attracted by amagnet16 at the base of the trench, holding the product against the mold surface during foaming. Theguide walls46 are spaced to bear against the sides of the trench, positioning the product.
• Referring next toFIGS. 17 and 18, moldedclip product450 has a series of pairs ofprojections452 extending from abase454 and defining a central channel extending along the product and sized to receive and retain a listing bead.Wings456 extend from either side edge of the base and definecorrugations118 having a period about equal to the spacing ofprojections452. Theproduct460 ofFIGS. 19 and 20 is identical but with a higher frequency ofcorrugations118 along the wings, in this case about three corrugation cycles perprojection452.
• FIGS. 21-23 illustrate another example of a fastener product500 with non-continuous (segmented) angled wings. Fastener strip500 features an array offastening elements110 disposed between two sets of staggered, segmentedwalls502, all extending from a moldedresin base102. This particular example shows three segmented walls on either side of the array, but other arrangements are contemplated. The segmented walls define a tortuous path between gaps, slowing and eventually stalling a flow of foam to help avoid flooding the fastener elements in the molding process. Details of various arrangements of segmented walls and their function can be found in U.S. Pat. No. 8,795,564, the contents of which are incorporated herein in their entirety.
• The castellated or segmented wings of product500 differ from those shown in U.S. Pat. No. 8,795,564 in that they extend from either edge ofbase102 extend at an angle toward the back side of the product, as with some of the different wings discussed above. The constant thickness wing segments each also features at least one undulation at its outer edge, such that even were the wing segments to lie against a flat surface portions of each wing segment would be spaced from the surface to form a small gap. Three magnetically attractable wires orcords60 are embedded in the product and provide magnetic attraction to a mold magnet.
• The fastening products described above may be used in a variety of fastening applications. For example, in addition to conventional foam molding applications, the arrangements of the fastening elements and walls can also be employed on a rigid fastening surface, such as injection molded fastening products. The following description provides details of an example application of a fastening product having the types of configurations discussed above.
• As shown inFIG. 24A,fastener product200 is placed on aflat surface12 of amold pedestal10.Mold pedestal10 is disposed in the interior space of amold cavity14.Fastener elements110 of the product face the mold pedestal surface. As described above, the fastener elements are arranged on the surface of the supporting base in an array betweenbarrier walls104. The positioning of afastener product100 as inFIGS. 1-4 would be similar, but with the foam strips compressed against thesurface12 of the pedestal outboard of thebarrier walls104. At rest, thecorrugated wings106 of the fastener strip extend away from the pedestal surface. The magneticallyattractable fastener strip200 is held againstflat surface12 by amagnet16 embedded in the pedestal. Magnetic attraction may be due to magnetically attractable resin forming all or part of the fastener product, or may be due to some other magnetically attractable material (e.g., a metal shim, wire or mesh that is secured to or embedded in the base of the product).
• Liquid foam resin18 is introduced into themold cavity14.Liquid foam68 may constitute a single component, or there may be multiple components that are mixed as they are introduced into the mold cavity, or before. In some implementations, polymeric foams (e.g., polyurethane foam, latex foam, and the like) are used. As shown inFIG. 24B, the liquid foam expands to fill the mold cavity. In some examples, the mold cavity can include a number of vents (not shown) to allow gas displaced by the expanding foam to exit the mold cavity. Suitable venting arrangements for the mold cavity are disclosed in U.S. Pat. Nos. 5,587,183 and 7,878,785, the entire contents of which are hereby incorporated by reference.
• As the liquid foam fills the mold cavity, the foam encompasses the angled wings of the strip, which become embedded in the cured foam. The barrier walls and end gaskets effectively seal against the flat pedestal surface. Accordingly, the flowing foam is inhibited from flooding the fastener elements. The molding of foam about the fastener product ofFIGS. 1-4 is similar, but the liquid foam contacts the foam strips and end gaskets of the product, which are held compressed against the pedestal surface, and partially penetrates into the open cells of the foam.
• Referring toFIG. 24C, a moldedfoam article20, as removed from the mold cavity, hasfastening product200 embedded in a trench defined by the mold pedestal. The perimeter of the fastener product is surrounded by foam. Foam also surrounds and bonds to the edge wings of the fastener strip, anchoring the fastening product to thefoam article20. The barrier walls of the fastening product form flow barriers to inhibit, if not prevent, foam from contacting the interior fastening elements. As a result, thefastener elements110 remain exposed and functional to releasably engage with fibers of a mating component (not shown) to form a hook-and-loop fastening.
• Other appropriate molding techniques and apparatus can be used to form a molded article with an incorporated fastener product. For instance, in some examples, the fastening product can be placed in a trench, as discussed above with respect toFIG. 16.
• The fastener products disclosed herein can be formed as flexible, continuous strips or sheets of material in a continuous roll molding process. Referring toFIG. 25,manufacturing apparatus700 has anextruder barrel702 that melts and forces amolten resin704 through a die and into a nip708 between apressure roller710 and acavity roller712.Cavity roller712 has cavities defined about its perimeter that are shaped to form the fastener elements (or at least, fastener element preforms) of the product, and other cavities that are configured to form the walls of the product, as the base substrate is formed on the outer surface of the cavity roller. Pressure in the nip forces the molten resin into the various cavities, leaving some resin remaining on the cavity roller surface to form the product base and wings. The resin travels around the cavity roller, which is chilled to promote resin solidification, and the solidified product is then stripped from the cavity roller by pulling the solidified fastener elements and walls from their respective cavities and passing the formed but pliable strip about a strippingroller706. In many cases the cavity roller will be of a diameter of between 30 and 50 centimeters, and the fastener elements and walls will be less than 1.5 millimeter in height (as described above), to give a sense of perspective.
• After the continuous length of fastening material is formed, it is passed over aninfrared heating lamp720, which softens at least the portions of the strip to become the wings, and then passes directly into a crimping station in which pressure between two nested andcounter-rotating crimping rollers722 that apply rolling pressure to emboss or otherwise impress the corrugation pattern into the portions of the product that will become the wings. The crimped product next passes through an end-formation station where a sonic horn (either a reciprocating horn or arotary horn724 as shown) obliterates the standing walls and fastener elements, such as by causing the resin of the walls and fastener elements to flow downward and become a part of the base, in discrete regions that will become the end regions of the final product. Onenozzle726 then intermittently sprays an adhesive only on the regions acted upon by the sonic horn, and anothernozzle728 continuously lays beads of hot melt adhesive onto the corrugated portions of the product that will become the wings. Once the adhesives have been applied, a continuous layer ofopen cell foam730 is laid onto the product and pressed onto the corrugated and end regions. The composite product next moves into a cuttingstation732, where the non-adhered portions of the foam strip are removed with aknife734, leaving the fastener element arrays exposed and bounded by foam extending along both longitudinal edges of the strip and by foam overlaying the sonically obliterated regions.
• The continuous strip next moves to a bending/slitting station, where appropriately shapedrollers736 plastically bend the wing regions of the strip toward the back side, out of the plane of the base of the strip. The process up to this point may be configured to form a double wide strip with two fastener element arrays and sets of barrier walls, joined by a middle region that is split at the bending/slitting station to separate the strip into two widths. The bent strip is then severed into lengths by slicing the strip midway through each sonically processed end region, producingdiscrete fastener products100 of the form shown inFIGS. 1-4.
• The products described herein in which the base is formed of a material comprising a magnetically attractable substance, such as an iron or magnetite powder, dispersed throughout a synthetic resin as a nanosuspension or reinforced nanocomposite material, such asfastener product100 ofFIGS. 1-4,fastener product200 ofFIGS. 8 and 9, andfastener product300 ofFIGS. 10-12, can be advantageously configured for improved foam retention strength. We have found that foam nucleating and curing against such resins can form weak spots near the fastener product, resulting in the foam failing when an attached loop material is detached for adjustment during installation, for example. In such cases, the foam may adhere well to the fastener product, but fail just behind the adhered layer of foam cells. Without being bound to any particular theory, we believe that such foam failures may be caused or exacerbated by the rate of cooling of the foam against the back of the magnetically attractable fastener product base.
• To help avoid such failures, the portion of the fastener product forming the substrate from which the fastener elements and other related projections extend (i.e., thebase102 of the products described above), should have a specific areal heat capacity, at 50 degrees C., of between about 15 and 65 milli-Joules per square centimeter degree C. This property is determined without regard to fastener elements or walls or other projections extending from the base, and without regard to any selvedges or wings of thinner cross-section than the base. It should be calculated to include any substance or layer provided on the back side of the resin base for contact with the foaming resin, as well as the material containing the magnetically attractable substance. It should also be calculated over a contiguous area of at least two square centimeters, or more if required to account for any repeating patterns of thickness variation. For example, to calculate this parameter for a fastener product having a base of a substance having a specific heat capacity of 1.52 Joules per gram degree C. and a density of 1.44 grams per cubic centimeter, and a nominal thickness of 0.25 mm, the specific areal heat capacity would be 54.7 milli-Joules per square centimeter degree C.
• It will be seen by those skilled in the art that many embodiments taking a variety of specific forms and reflecting changes, substitutions, and alternations can be made without departing from the spirit and scope of the invention. Therefore, the described embodiments illustrate but do not restrict the scope of the claims.

Claims (17)

1. A male touch fastener strip having a front fastening face and a rear face, the strip comprising:

an elongated base;

a field of exposed male fastener elements each having a stem extending from the base on the front fastening face of the strip; and

a pair of wings, each wing extending from a respective longitudinal edge of the base outboard of the field of fastener elements;

wherein each wing defines discrete corrugations extending in a series along the fastener strip and forming corresponding undulations in the rear face of the strip along longitudinal edge regions of the fastener strip.

2-6. (canceled)

7. The touch fastener strip ofclaim 1, wherein the corrugations feature a saw tooth profile at outboard edges of the wings.

8-11. (canceled)

12. The touch fastener strip ofclaim 1, wherein each wing carries a respective strip of foam adhered to the wing on a same side of the fastener strip as the fastener elements.

13. The touch fastener strip ofclaim 12, wherein the strips of foam overlay the corrugations.

14. The touch fastener strip ofclaim 12, wherein the fastener strip has longitudinal end regions in which the front fastening face of the strip is covered by foam forming, in cooperation with the foam strips, an end barrier of the fastener strip.

15-20. (canceled)

21. The touch fastener strip ofclaim 1, wherein at least a portion of each undulation extends at least partially rearward of the side of the base opposite the fastener elements.

22. The touch fastener strip ofclaim 1, wherein the series of the corrugations comprises a frequency of between 4 and 20 corrugation cycles per inch along the fastener strip.

23. The touch fastener strip ofclaim 1, wherein the wings are each angled, in an unloaded state, toward the rear face of the strip.

24. The touch fastener strip ofclaim 23, wherein the wings each form a midpoint angle of between about 5 and 80 degrees with respect to the lateral plane.

25. The touch fastener strip ofclaim 1, wherein the corrugations define a corrugation amplitude, at outer edges of the wings, of at least twice a nominal edge thickness of the wings.

26. The touch fastener strip ofclaim 1, wherein the base is of a material comprising a magnetically attractable substance dispersed throughout a synthetic resin.

27. The touch fastener strip ofclaim 26, wherein the magnetically attractable substance comprises between about 30 and 40 percent of the material, by weight.

28. The touch fastener strip ofclaim 26, wherein the wings are formed of the material, the wings and base together forming a contiguous mass of the synthetic resin.

29. The touch fastener strip ofclaim 1, further comprising longitudinal walls rising from the base on either side of the field of male fastener elements and inboard of the wings.

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